Rotary wing aircraft



Dec. 15, 1942. c. G. PULLIN ROTARY WING AIRCRAFT e SheetS -Sh'eet 1 Filed May 25, 1940 9U z \ficwc a 20 1, i MM? 5 w 00 M W m. n h

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ROTARY WING AIRCRAFT 4 Filed May 25, 1940 a Sheets-Sheet 6 Patented Dec. 15, 1942 4 UNITED STAT ES PATENT OFFICE ROTARY WING AIRCRAFT Cyril George Pullin, Genista, Newton Mearns,

Scotland, assignor to Antogiro Company pf America, WillowGrove, Pa., a corporation of Delaware Application May 25, 1940. Serial No. 337,171

' In Great Britain March 18, 1939 1 1 28 Claims.

The present invention relates to rotative wing aircraft, more particularly of the type in which the sustaining rotor or rotors are normally power driven during flight.

An object of this invention is to provide means for preventing the re-application of power to the unit or rotor'transmission during flight. v The present invention contemplates the employment of means responsive to the torque being transmitted to the rotor blades to stop or greatly reduce the power of the power unit,

It is known that, in a rotor having drag articulations between the blades and .the hub, move- 'rotor or rotors following a failure of the power 7 In the drawings: Fig. 1 is a diagrammaticplan view showing the invention as applied to an aircraft having a pair of sustaining rotors disposed on either side of the axis of-symmetry of the aircraft;

Fig. 2 is a fragmentary axial sectional view through the torque responsive device;

Fig. 3 is a fragmentary view, partly in section,

' taken at right angles to Fig. 2 and" showing the went about such articulations occurs accordin to whether or not torque is applied to the rotor. During autorotation the blades, under the influence of centrifugal and autorotative' forces, take up positions in advance-of the radial positions, but when the rotor is driven by a power unit the blades lag behind the radial positions by an amount dependent on the angle of incidence of the blades. In one form of construction in accordance with this invention-this movement about the drag articulations is utilised to actuate a switch which operates to stop the power unit in the event of the failure of the latter or of the transmission which would allow the rotor blades to move forwardly from the lagging positions central part onlyof the mechanism of Fig. 2:

Fig. 4 is a sectional view on the line 1111-4111 of Fi Fig. 5 is a sectional view of a control box for the power unit for use in connection with the torque responsive device, illustrated in Figs. 2 to 4, with a side cover removed;

Fig. 6 is a sectional plan of the control box, illustrated in Fig. 5. The control levers are dis posed vertically;

. Fig. 7 is a sectional view of the control box of Figs. 5 and 6, the control levers being nearly vertical;

Fig. 8 is a somewhat diagrammatic section of ment;

Fig. 11 is aplan view showing the blade in the position which it assumes while torque is being applied to the rotor; and

Fig. 12 is a view similar to Fig. 11 showing the blade'in the position which it assumes during of the power unit, this device operates to stop the power unit 'or to reduce its power output and so prevent the re-application of normal driving torque to the rotor or rotors.

It is to be understood that means are provided for disconnecting the rotor or rotors from the power unit so that in the event of a failure of the power unit or rotor transmission, the rotor or rotors can o erate autorotatively to provide suflicient lift to enable the aircraft to be landed safely.

The accompanying drawings show by way of example two embodiments of the present invenautorotation of the rotor.

Referringto Figs. l'to 9. An aircraft has a pair of sustaining rotors I00 and It, with blades The hub of each of the rotors includes a freewheel coupling and a rotor brake which are not illustrated but which are well known inthe art. For instance a suitable construction of hub is described and claimed in my copending'U. S. application Serial No. 337,381,. filed May 27, 1940, corresponding to British application- No. 7,609 dated March 9,1939. Other known forms of rotor hubs having freewheel couplings and/or rot or brakes are disclosed in such issued patents as Bennett, et a1. 2,105,682, Campbell 2,127,105, Pccker 2,150,129, Ciferva 2,155,409, Larsen 2,183,- 119, and Ray 2,216,163. The rotor I00 is driven through a shaft I03 from a gearbox I04 on the centre line of the aircraft, while a similar shaft I05 drives the rotor IN. The gearbox I04 has a forward extension I I6 enclosing the torque responsive device, illustrated in Figs. 2, 3 and 4. The gearbox I04 is driven through the torque responsive device I06, shaft I01 and a fluid coupling I08 from a power unit I09, having a magneto H and a fluid pressure pump III. Abrake drum H2 is mounted on the shaft I01 and is controlled by a lever in the pilot's cockpit which also controls the rotor brakes which are applied simultaneously with the brake II 2.

Driven by bevel gearing H3 and H4 from the shaft I03 is a governor unit II hereinafter described with reference to Fig. 8, and which is connected by a pipe 295 to a pitch control'unlt II 6 mounted above gearbox I 04. The pitch change unit H6 is diagrammatically illustrated in Fig. 9 and has a pair of chain wheels I and I2I coupled respectively to the rotors I00 and IOI by chains I22 and I23 and I24 and I25 respectively so that turning of the chain wheels I20 and I2I in opposite directions causes simultaneous pitch change of the two rotors in the same sense. While the pitch change mechanism.

of the rotor hubs is not illustrated reference may be had to my copending application aforesaid for a full disclosure of a suitable construction. Other known constructions involving pitch change mechanism are disclosed in several of the above-mentioned patents, including Pecker 2,150,129 and Cierva 2,155,109.

Electrical connections from the torque responsive device I06 are brought to a power unit control box I26 having control levers I21 and I28 which are coupled to thepower unit I09 in the customary manner. Further electrical connections run from the power unit control box I26 to the low tension circuit of the magneto IIO of the power unit. The arrangement of the control box is such that in certain positions of the levers I21 and I28, the torque responsive device I06 is prevented from stopping the power unit I09 in the event of a momentary failure of the latter.

Referring to Figs. 2, 3 and 4. The shaft I01 from the fluid coupling I08 is supported by a journal bearing I30 in the casing I3I of the torque responsive device, the bearing I30 being secured on the shaft I01 by a ring I 3I' and by by screwed studs I34 to the casing I3I The shaft I01 is extended towards the gearbox by a part- I35 of reduced diameter, having external splines I36 and having at its extreme end a spigot bearing surface I31 provided with oil grooves I38. Axially slidable along the splines I36 of the part I35 of the shaft I41 is a clutch annulus I40, having at its left hand end a groove I4l, engaged by a striking arm I42 mounted on a shaft I43 and secured thereto by a pin I44. The shaft I43 is journalled in lugs I45 provided in the casing I3I. One end of the shaft I43 projects beyond the casing I3I and carries a clutch operating arm I46, by which the clutch can be thrown out to disconnect the drive from the power unit to the rotors. An outer clutch member I50 securedby an annular member I32 and plate I33 secured 7 bolts I5I to a flange I52 of the clutch member nected to the strip I55 by a bolt I58. A second slip ring I59 is connected electrically to the clutch member I40. The striking arm I42 carries a block I60 of insulating material which is secured to one of the pins I6I, which engages the recess I in the clutch member I40, by a screw nut I62 and which has recesses I63 and I64 in which brushes I65 and I66 are slidable. The brush I65 is pressed by a spring I61 into contact with the slip ring I59, while a similar spring I68 presses the other brush I66 into contact with the slip ring I51. v

Electrical connections I69 and I10 are taken from the vbrinshes I 65 and I66 respectively through the casing I3I and thence to the power unit control box I26 and to the power unit I09.

The inner surface of the outer clutch member I50 is provided with two sets of inwardly extending lugs I and I8I, each of which has three lugs. When the clutch is'in the engaged position the lugs I80 are able to engage the outwardly extending lugs I82 on a flange I83, formed on a stub shaft I84, which has a bevel wheel I85 secured by a key I86 and a screwed ring I 81 to its right hand end. The boss of the bevel wheel I85 is supported by a bearing I88 carried by'a web I89 within the casing of the gearbox I04 which is secured by studs I90 to the casing I3I of the torque responsive device.

The lugs I8I are able to engage a series of lugs similar to the lugs I82 formed on the flanged end I9I of a shaft I92 concentric with the stub shaft I84 and which carries at its right hand end a bevel wheel from which the shaft I05 to the rotor IN is driven. A liner I93 held within the hollow shaft I92 cooperates with the spigot bearing surface I31 of the extension I35 of the shaft I01, When the clutch operating arm I 46 is actuated to disengage the clutch, the clutch annulus I40 and outer clutch member I50 are moved to the left against the action of a spring I41 to a position in which the lugs I80 are able to revolve freely without making contact with the lugs I82. In this position the lugs I80 are about midway between the lugs I82 and the corresponding lugs on the flanged end I93 of the shaft I92.

As seen in Fig. 4, a second series of lugs I95 are formed on the flange I83 intermediately between the lugs I82. with plungers I96 disposed tangentially which have an end I91 which coacts with the lugs I95 and which are surrounded-by coil springs I98 which urge the plungers inwardly. The outer end of the plunger is slidable in a metal bush I99 screwed into a part formed in the outer clutch member I50 for this purpose, as shown in Fig. 4.

There are three of these plungers spaced'equidistantly around the periphery of the outer clutch member I50. Two of these plungers are extended at their outer ends by screw threaded parts carrying screw nuts 200 which secure in position contact arms 20I. When the plungers are in their innermost positions the free ends of these contact arms are able'to make contact with the strips I55, supported by the insulating block I53 mounted on the outer clutch member. Since the plungers I96 are in electrical connection with the outer clutch member I50 it will be seen that the circuit between the brushes I65 and I66 is com- ,pleted. This position of the plungers I96 is illusobtaining when no torque is beingtransmitted through the device. When, however, the rotors are being driven, relative movement between-the These lugs I 95 cooperate stub shaft I84 and the outer clutch member I56 occurs as the lu s I 66 move round to come into contact with the lugs I82, and at the same time the lugs I95 cause outward movement of the plungers which results in separation of the contact arms 26I from the stri'ps I55, thus opening is illustrated in Figs. 5, 6 and '1. The control box comprises a backing plate 2I6 to which a spindle 2 is secured by rivets 2I2. The control levers I21 and I28 of the control box are mounted on the spindle 2I2 which carries bearing rings 2I8 on either side of each of the control levers and spacing washers 2I4. Similarly mounted on the spindle 2| I is a plate 2I5 to which a sector 2I6 of insulating material is secured by bolts 2I1. The control levers, bearing rings, spacers and plate 2I5 are secured in position on'the spindle 2 by a screwed ring 2I8 which is carried by a screw thread 2I9 on the spindle 2I I. Rotation of the spacers 2I4 relatively to the spindle is prevented by providing .them with inward projections which engage keyways 226 extending along the spindle 2I I.

The sector 2I6 of insulating material has secured to it,by screws 225 two arcuate contact strips 226 and 221 which, as will be seen from Fig. 5, do not extend the whole way around the sector 2I6. The throttle control lever I21 has a block of insulating material 228 secured to it by studs 229 and is provided with a recess 236 having a metal liner 23I which forms a housing in which a brush 232 is slidable. The brush 232 is urged downwardly onto the contact strip 221 by a coil spring 233 which is housed within the liner 23L A bolt 234 and nut 235 secure the liner 23I in position and provide connection between the latter and a spring strip 236. A second brush 231 is similarly mounted in a second recess in the block 228 and is connected by a bolt 238 and nut 239 to a second spring strip 246.

The spring strip 236 presses against a contact annulus 24I carried by the front cover plate 242 of the control box and joined to a terminal 243. The spring strip 246 makes a sliding'contact with a second contact annulus 244, also-carried by the front cover plate 242 and connected to a terminal (not shown) mounted below theterminal 243. Secured to a-terminal 256 (see Fig. is a spring contact strip 25I which presses-against the arcuate contact strip 226 while a similar strip (not visible) is secured to a terminal 252 above the terminal 256 and makes contact with the second arcuate contact strip 221.

Attached to the lower end ofthe mixture control lever I28 by a pivot 255 is a link 256 secured to the mixture control rod 251 coupled to the power unit by an adjustment comprising a screw by a screw nut 265 a pivotal connection 266 to' which a rod 261 is secured. The rod 261.is coupled to the lever (not shown) for applying the transmission brake H2 and the rotor brakes and is arranged, when the brakes are applied, to rotate the plate II5 anti-clockwise, as seen in Fig. 5, to a position in which the brushes 232 and 231 are always in contact with the contact strips 226 and 221 no matter what the position of the throttle lever I21, thereby preventing starting of the power unit I69 while the brakes are on.

The operation of the control box is as follows.-

When the throttle control lever I21 and plate 2I5 are in the positions shown in Fig. 5, the brushes 232 and 231 are out of contact with the contact strips 226 and 221 so that the circuit I from the torque responsive device I66.to the mag-- neto II6 of the power unit I68 is broken. This position of the throttle control lever I 21 corresponds to the full throttle or rotor starting condition. When, however, the throttle control lever I21 is moved to the normal cruising position, the

l brushes 232 and 231 make contact with the conat which the brushes 232 and 231 make contact -via the contact annulus 24I, spring 236, brush 232' and contact strip 221. The angular position with the end of the contact strips 221 and 226 can be altered by moving the rod 261 which is coupled to the lever for applying the transmission and rotor brakes as above described. During starting the power unit cannot be switched oil by the torque responsive device I 66 as the electrical circuit from the latter to the 'power unit Fig. 8 shows diagrammatically the construc-' tion of the governor unit II5 which comprises a casing 216 through which passes a driving shaft 2" having at its inner end a bevel pinion 212 meshing with a bevel wheel 213 secured to a plate 214 rotatable about a vertical axis and having on its upper surface a pair of lugs 215 to which are pivotally attached a pair of governor weights 216. Each governor weight has an inward extension 211 which lies under a collar 218 at the upper end of a piston valve rod 219 which is vertically slidable in a bore 286 in the casing 216. The piston valve rod 219 is urged downwardly by a compression coil spring 28I, the lower end of which abuts against the collar 218 while the upper end abuts against a rack member 282 which is vertically slidable in guides 283 formed within the upper part of the casing. The rack of the rack member is engaged by a toothed sector 284 carried by a shaft 285 on which is mounted a wheel 286 coupled to a pilots control for adjusting the equilibrium speed of the governor unit.

Communicating with the upper part of the bore 286 is a duct 281 which is connected to the pressure side of the fluid pump I'll by a pipe 268. A duct 289 connected by a pipe 296 to the suction side of the pump III communicates with an enlargement 29I at the lower end of the bore rotated at the adjusted equilibrium speed occupies the position shown in Fig. 8. In this position the space surrounding the reduced part 293 of the piston rod, which is always in communication with a duct, 294 continued as a pipe 295 to the pitch control unit H6 is not connected to either the pressure or the suction side of the pump III.

If, however, the speed of the shaft I03 increases, the governor unit driven through the bevel drive II3, Ill, is driven more quickly, causing the governor weights 216 to move outwardly so that their inward extensions 2'" move the collar 218 upwardly against the action of the spring 28I thereby moving the piston valve rod 219 upwardly to a position in which the duct 28'! is put into communication with the duct 294 allowing pressure fluid to pass to the pitch control unit. Conversely, should the speed of the shaft I03 be reduced, the governor weights 2I6 move inwardly under the action of the spring 28I allowing the piston valve rod 219 to move downwardly. to a position in which the duct 294 is put into communication with the duct 289 permitting fluid to return from the pitch control unit II6 to the suction side of the pump III.

The pitch control unit I I6 is illustrated in Fig. 9. (Features of this unit are claimed in my copending application 331,318, filed April 24, 1940.) It comprises a cylinder 300 in which a piston "I is slidable and which communicates with the governor unit I I through the pipe 295. The pis ton 30I is connected by a journal and thrust bearing 302 to a sleeve 303 having external left and right hand screw threads 304 and 305 which are engaged respectively by projections 306, 301 formed on rack members 308 and 309. The rack 3I0 of the rack member 308 meshes with a pinion 3 carried on a stub shaft extending through the casing of the pitch control unit to a chain wheel I20 coupled by cables I22, I23 to the pitch control of the rotor I00. Similarly the rack 3I3 of the rack member 309 meshes with a pinion 3H mounted on a stub shaft carrying a chain.

wheel I2I coupled by cables I24, I25 to the pitch control of the rotor IOI. A construction of rotor hub especially adapted for use in this way is described in m copending British app ication No. 7,609 of 1939and its corresponding U. S. application No. 337,38

A coil spring 3I6 is arranged to urge the piston 30I towards the left, as seen in Fig. 9, one end of the spring lying in a recess 3I'I in the back of the piston 30I while the other presses against a collar 3I8 formed on the elongated shank 3I9 of a sprocket 320 which is mounted so as to be rotatable but not axially movable relatively to the casing of the pitch control unit. The shank 3I9 of-the sprocket 320 has a keyway' 32I engaged by an inwardly projecting key 322 formed on the sleeve 303 which is thereby secured to the sprocket for rotational movement but which is capable of moving axially relatively thereto.

When fluid pressure is applied to the cylinder 7 300 through the pipe 295 from the governor unit II5, the piston 30I moves to the right, as seen in Fig. 9, carrying with it the sleeve 303 and rack members 308 and 309, thus causing rotation of the pinions 3H and 3I5 and hence of the chain wheels I20 and I2I in opposite directions. This is arranged to cause an increase of pitch of each of the rotors I00 and IN. Conversely, when the speed of the rotor shaft I03 is reduced, the fluid pressure within the cylinder 300 is reduced by the action of the governor unit allowing the pisasoaseo ton 30I to move under the action of the spring 3I6 to reduce the pitches of both rotors, causing a reduction in the torque which they absorb and tending to allow the speeds of the rotors to return to normal. This normal speed of operation can be altered by the use of the pilot's control coupled to the wheel 286 for altering the equilibrium of the governor unit.

Should the power unit fail the torque transmitted by the torque responsive device I06 will be reduced allowing the driving lugs I80 and I82 on the outer clutch member I50 and flange I83,

, respectively, to separate under the action of the coil springs I98 which urge the plungers I96 inwardly. This inward movement of the plungers I96 allows the contact arms 20I to touch the strips I55 and so to complete the circuit between the connections I69 and H0 from the brushes I and I66. Since during normal flight when the throttle is not fully open, the electrical circuits between the terminals of the power unit control box are also completed, this completion of the circuit between the brushes I65 and I 66 will cause the low tension winding of the magneto to be short circuited so stopping the power unit. During starting of the rotors, however, owing to the fact that the circuits within the power unit control box are notcompleted a reduction in torque will not result in stopping of the power unit.

When the power unit is stopped the freewheel clutches incorporated in the rotor hubs will allow the rotors to overrun the drive but owing to the large angle of incidence of the blades in the helicoptering setting the rotors' will tend to slow down rapidly. The stopping of the power unit will also stop the shaft I03 from which the governor unit H5 is driven, thus causing the latter to operate to put the cylinder of the pitch control unit into communication with the suction side of the fluid pump thereby reducing the pitches of both rotors. The position which the piston 30I takes up when the fluid pressure in the cylinder 300 is released is arranged to correspond to rotor pitches within the. autorotative range so that each rotor will continue rotating and provide suflicient lift to allow the aircraft to he landed safely.

Lateral control of the aircraft by altering the pitches of the rotors in opposite senses is provided by turning the sprocket 320, causing the sleeve 303 to turn and bring into play the left and right handed screw threads 304 and 305 which cause movement of the rack members 308 and 309 in opposite directions, resulting in an increase of the pitch of one rotor with a corresponding reduction in pitch of the other rotor. The sprocket 320 will normally be coupled to a pilot's control column so that movement of the control column to the left causes an increase of the pitch of the starboard rotor with a corresponding reduction in pitch of the port rotor and vice versa.

Referring to Figs. 10, 11 and 12 which show an alternative construction. A sustainingrotor has a rotative hub 50 which is driven during normal flight from a shaft 52 through a gearbox 5I, which advantageously incorporates a freewheel clutch. In the construction illustrated, the rotor has two blades, each of which has at its root end a link 53 connected to the hub part 50 by a flapping articulation 54. The link is connected to the root member 55 of the blade 56 by a drag articulation 51, the axis of which is generally at right angles to the axis of the flapping articulation 56.

An extension of the flapping articulation pivot carriesan arm 60 which is arranged to follow movements of the link 53 about said flapping articulation. Mounted at the outer end of the arm 60 is a housing 6| from which projects a contact plunger 62, which is urged in a downward direction, as seen in Figs. 11 and 12, by a spring 63. From thecontact plunger 62 a lead 64 extends to aslip ring 65 carried by a disc of insulating material 66 secured to the rotative hub part 50. Mounted on the casing of the gearbox is a contact plunger 81 which is pressed into contact w .h the slip ring 65 by a spring 68 which is enclosed within a casing 69. From the contact plunger 61 a lead extends to the means for stopping or reducing the power output of the power unit. For instance it may be connected to the magneto of the power unit or to a relay which operates to reduce the throttle opening.

While the rotor is being driven, each ofthe blades assumes a lagging position generally as indicated in Fig. 11, the extent of the lag depending upon the angle of incidence of the blade and upon the applied torque. In this lagging position the contact plunger 52 is separated from the blade root member 55. When the rotor is autorotating the blades move forward to a generally radial position, as indicated in Fig. 12. In this position the blade root member .55 makes contact with the contact plunger 62, thus complating an electrical circuit from the casing of normally power driven during flight, a power unit, a power transmission from the power unit to the rotor, torque responsive means included in the power transmission comprising a spring which is compressed during the'application of normal torque to the rotor, a plunger surrounded by the spring and carrying a contact arm which I is adapted to connect with a slip ring on expansion of the spring, when the torque is reduced, thereby closing an electric circuit preventing the reapplication of the normal driving torque to the rotor.

5. In an aircraft, a pair of bladed sustaining rotors normally power driven during flight, a

rotors normally power driven during flight, a

' power unit, a power transmission from the power the gearbox 5| through the hub member 50, link a 53, blade root member 55, contact plunger 62,

the power unit to the rotor, means operative in response to a substantial decrease in the torque transmitted to the rotor blades to prevent the reapplication of the normal driving torque, and means automatically operative upon substantial decrease in rotor R. P. M. to lower the mean blade pitchangle.

2. In an aircraft, a variable pitch bladed sustaining rotor normally power driven during flight, a power unit, a power transmission from the power unit to the rotor, means incorporated in the power transmission operation in response to a substantial decrease in the torque transmitted to the rotor to prevent the reapplication of the normal driving torque, and means automatically operative upon substantial decrease in rotor R. P. M. to lower the mean blade pitch angle. a

3. In an aircraft, a bladed sustaining rotor normally power driven during flight, a power unit, a power transmission from the Power unit to the rotor, torque responsive means included in the power transmission and comprising a spring which is compressed during the application of the normal torque to the rotor and which when the torque is reduced expands to close an electric circuit controlling the operation of the power unit, thereby preventing the reapplication to the rotor. of the normal driving torque.

4. In an aircraft, a bladed sustaining rotor unit to each of the rotors, torque responsive means included in the power transmission to each of the rotors comprising springs which are compressed during the application of normal torque to the rotors, plungers-surrounded by each spring and carrying contact arms which are adapted to connect with a slip ring on expansion of the springs when the torque is reduced, thereby closing an electric circuit preventing the reapplication of the normal driving torque to the rotors.

7. In an aircraft, a pair of bladed sustaining rotors normally power driven during flight, a power unit including a, magneto, a power transmission from the power unit to each of the rotors,

torque responsive means included in the power transmission to each of the rotors comprising springs which are compressed during the application of normal torque to the rotors, plungers surrounded by each spring, and carrying contact arms which are adapted to connect with a slip ring on expansion of the springs when the torque isreduced, thereby short-circuiting the low tension winding of the magneto of the power unit,

stopping the latter and preventing the reappli-- cation of the normal driving torque to the rotors.

8. In an aircraft, a bladed sustaining rotor normally power driven during flight, a power unit, a power transmission from the power unit to the rotor, torque responsive means included in the power transmission comprising a spring which is compressed during the application of normal torque to the rotor, a plunger surrounded by the spring and carrying a contact arm which is adapted to connect with a slip ring on expansion of the spring when the torque is reduced, thereby short-circuiting the low tension winding of themagneto of the power unit, stopping the latter and preventing the reapplication of the normal driving torque to the rotors.

9. In an aircraft, a bladed sustaining rotor normally power driven during flight, a power unit, a power transmission from the power unit to the rotor, and means operative upon said unit in response to a substantial decrease in the torque transmitted to the rotor blades to materially reduce the power output of said unit, whereby to prevent the'reapplication of the normal driving torque to the rotor.

10. In an aircraft, a bladed sustaining rotor normally power driven during flight, a power,

unit, a power transmission from the power unit to the rotor, means operative in response to a. substantial decrease in the torque transmitted to the rotor blades to prevent the reapplication of normal driving torque, a power unit throttle control and an interconnection between the throttle control and the torque responsive means for preventing the operation of the latter when the power unit throttle is fully open for starting P rp ses.

12. In an aircraft, a power driven during flight, a power unit, a power transmission from the power unit to the rotor, the latter having a hub and blades connected to the hub by drag articulations and means responsive to movement of the blades about said drag articulations in the event of a decrease of the applied torque to a sub-normal value operative to prevent the reapplication to the rotor of the normal driving'torque.

13. In an aircraft, a sustaining rotor normally power driven' during flight, a power unit, a power transmission from the power unit to the rotor, the latter having a hub and blades connected to the hub by drag articulations, means operative in response to movement .of a blade from the lagging position which it assumes while torque is being applied to the rotor to a generally radial position to prevent the reapplication to, the rotor of the normal driving torque.-

14. In an aircraft, a sustaining rotor normally power driven during flight, a power unit, a power transmission from the power unit to the rotor, the latter having a hub and blades connected to the hub by drag articulations, flapping articulations between, each blade and the hub, an arm arranged to partake of flapping movements of a blade about its flapping articulation and carrying a contactfadapted to make contact with the blade root in the event of movement .of the blade from the lagging position which it assumes while torque is being applied to the rotor to a generally radial position, and an electric circuit including said contact and the blade root for preventing the reapplication to the rotor of the normal driving torque.

15. In an aircraft, a sustaining rotor normally power driven during flight, a power unit including a magneto, a power transmission-from the power unit to the rotor, the latter having a hub and blades connected to the hub by drag articulations, flapping articulations between each blade and the hub, an arm arranged to partake of flapping movements of a blade and carrying a contact adapted to make contact with the blade root in the event of movement of the blade from the lagging position which it assumes whiletorque is being applied to the rotor to a generally radial position, and an electric circuit including said contact and the blade root arranged to short circuit the low tension winding of the magneto to prevent the reapplication to the rotor of the normal driving torque. i

16. In an aircraft. a sustaining rotor normally power driven during flight, a power unit including a magneto, a power transmission from the power unit to the rotor, the latter having a hub sustaining rotor normally and blades connected to the hub by drag articulations, flapping articulations between each blade and the hub, an arm arranged t partake of flapping movements of a blade and carrying a contact adapted to make contact with the blade root in the event of movement of the blade from the lagging position which it assumes while torque is being applied to the rotor to a generally radial position, an electric circuit including said contact and the blade root arranged to short circuit the low tension winding of the magneto of the power unit to prevent the reapplication to the rotor of the normal driving torque, and a control box. for the power unit including an electric circuit which when the throttle lever is in the full throttle position prevents the shortcircuiting of the magneto.

17. In an aircraft, a bladed sustaining rotor normally power driven during flight, a power unit including a magneto, a power transmission from the power unit to the rotor, means responsive to a substantial decrease in the torque transmitted to the rotor operative to connect electrically a pair of terminals, a control box for the power unit including a throttle control movable about a' pivot axis, an arcuate contact strip carried by a plate rotatable about said pivot axis, a contact element mounted on the throttle control adapted to make contact with the arcuate contact strip, means for turning the plate into a position in which the contact element mounted on the throttle control no longer makes contact with the arcuate contact strip when the throttle control is in the full throttle position, and an electric circuit including in series said terminals, the contact element and the arcuate contact strip adapted to short circuit the low tension winding of the magneto of the power unit.

\ 18. man aircraft, a bladed sustaining rotor normally power driven during flight, a power unit including a magneto, a power transmission from the power unit to the rotor, a rotor brake included in said transmission, means responsive to a substantial decrease in the torque transmitted to the rotor operative to connect electrically a pair of terminals, a control box for the power unit including a throttle control movable about a pivot axis, an arcuate contact strip carried by a plate rotatable about said pivotcaxis, a contact element mounted on the throttle control adapted to make contact with the arcuate contact strip, a rotor brake lever, a link coupled to the latter and to the plate to rotate said plate to a position in which the contact element mounted on the throttle control can no longer make contact with the arcuate contact strip when the throttle control is in the full throttle position, and an electric circuit including said terminals, the contact element and the arcuate contact strip in series adapted to short circuit the-low tension incorporating a blade mounted with freedom for movement in a direction generally fore and aft within its rotative path of travel.

.gine is dependent, and means engine means to the rotor,

, mission means engine means to the rotor, and a torque responand further incorporating an engine means for driving the rotor, power on means for delivering torque from the engine means to the rotor incorporating an overrunnin clutch,

a control device on which operation of the enlead movements of the blade operative to condition the control device to stop the engine upon leading movement of the blade and to condition the control device for engine operation upon laggin movement of the blade.

21. A construction in acco 19, in which the engine control device comprises a magneto and in which said means responsive to lag-lead movements of the blade acts to render said magneto inoperative upon leading movement of the blade and to render said magneto operative upon lagging movement of the blade.

22. In an aircraft, a blade sustaining rotor, engine means for driving the rotor, power transmission means for delivering torque from the engine means to the rotor, a control device on which operation of the engine is dependent, and means responsive mitted to the rotor through said power transmission means to condition said control device (or engine operation and for engine stoppage.

23. In an aircraft, a blade sustainin rotor, engine means for driving the rotor, power transmission means for delivering torque a control device on which operation of the engine is dependent, and

in torque transthrough said power transmisto condition said control device for engine operation and for engine stoppage, said last means being operative to condition the control device to stop the engine means upon a subin rotor drivin torque. aircraft having a sustaining rotor, for driving the rotor, power transior delivering torque from the rdance with claim sion means 24. In an engine means sive device for controlling engine operation in a sense providing for termination of engine operation upon substantial drop in rotor driving torque.

25. An aircraft in accordance with claim 24, adjustable speed control for the engine means, and mechanism interrelating the operation of the speed control and of said torque responsive means and providing against operation of the torque to fluctuations in torque transfrom the respon ve responsive to lagmeans to shut of! the engine when the speed control is adjusted for high speed operation-oi theengine means. I

26. In anaircr it,--a variable pitch sustaining rotor adapted alternatively to be power driven with a relatively-high mean pitch setting and to be autorotationally actuated with a relatively low for delivering torque eluding a, device for rendering the transmission ineiiective during autorotational flight, a torque responsive device forcontrolling engine operation in a sense providing for termination of engine operation upon substantial drop in 'rotor driving torque, an adjustable speed control for the engine means, and mechanism associated with the speed control and with said torque responsive device for rendering the latter ineflective to shut off the engine when the speed control is adjusted for high speed operation of the engine. i

27. In an aircraft, a variable pitch ustaining rotor adapted alternatively to be power driven with a relatively high mean p'tch setting and to with a relatively low be autorotationally actuated pitch setting, engine means for driving the rotor, power transmission means for delivering torque from the engine means to the rotor including a free wheeling clutch for autorotational flight, a torque responsive device for controlling engine operation in a sense providing for termination of engine operation upon substantial drop in rotor driving torque, an adjustable speed control for the engine means, mechanism associated with the speed control and with said torque responsive device for rendering the latter ineffective to shut off the engine when the speed control is adjusted for high speed operation of the enthe mean pitch angle of substantial reduction in R. P. M. of the rotor below the high speed thereof corresponding to the high speed operation of the engine crease the mean pitch of the rotor blades.

28. In an aircraft,

gine, means for varying for driving the rotor, 'a control device on which dependent, and mechanism interrelating the operation of the rotor brake and the said control device and providing against starting of the engine when the rotor brake is applied. CYRIL GEORGE PUIJJN.

for drivin the aforesaid to de-.

a sustaining rotor, a rotor CERTIFICATE OF CORRECTION.

' fetent No. 2,509,589. December 15, 191m.

CYRIL GEORGE PULLIH;

It is hereby certified that error appeare in the printed specification pfthe above numbered patent requiring correction as fiolloivs! Page Z, first 1ine-6', e1 "engeges read --eng'age--; page 14., eecond'colmnn, line- 8, be-

. fbre fl f' 'insert --speed- PageLfirst column, lines 19 and 28, claims 22 and 25, for blade read --bladed; and that the said Letters Batent should be read with this correction therein that the aaine my conform to' the record ofthe case in the Patent Office.

Signed and sealed this 26th day of January, A. D. 1911.5.

Henryvgfhrsdale, (Seal) Acting commiseioner of Patentsi 

